You didn't read far enough because he specifically notes this. The 18th century started on January 1, 1701, therefore 1776 is indeed the 76th year of that centu

You didn't read far enough because he specifically notes this. The 18th century started on January 1, 1701, therefore 1776 is indeed the 76th year of that century, not the 77th, as the year 1700 is part of the 17th century.